auto scroll

基本解释

Second, if you want to drag the object to another program, how can the app tell the difference between that and the desire to auto-scroll?
其次，如果你想拖动对象到另一个程序，应用程序该如何分辨这种情况与自动滚屏呢？收藏。
To cure this, auto-scrolling should begin only after the drag-cursor has been in the auto-scroll zone for some reasonable time cushion—about a half-second.
应该只有在拖动光标进入自动滚屏敏感带时，对时间进行合理缓冲约半秒钟后再开始启动。
It would be better if the auto-scroll went faster the closer the cursor gets to the edge of the window (though it's also important to have a speed limit—it doesn't help anyone if it goes too fast).
当光标越来越接近边界时，滚屏速度就会越来越快（所以应该对最快速度有一个限制，速度太快对谁都没有好处）。

To make this work with auto layout, the meaning of the top, left, bottom, and right edges within a scroll view now mean the edges of its content view.
ENGADGET: Apple seeds iOS 6 beta 4 to developers: here's the changelog